2.17. Biogenic processing

2.17.1. BEIS3 processing

The SMOKE system uses a more advanced emissions modeling approach for biogenic processing than it uses for the other source types. For biogenic emissions, the temporal processing is a true simulation model driven by ambient meteorology and other data. SMOKE currently supports two methods for computing biogenic land use: BEIS2 and BEIS3. The overall processing performed by both these models is quite different from the processing done for anthropogenic source categories. BEIS2 and BEIS3 start with spatial allocation of land use data as the first processing step (which is the same as importing the raw inventory data for anthropogenic sources). They next compute normalized emissions for each grid cell and land use category. The final step is adjusting the normalized emissions based on gridded, hourly meteorology data and assigning the chemical species to output a model-ready biogenic emissions file. The following two subsections provide more detail about the two biogenic models in SMOKE and give references to additional detail elsewhere.

2.17.1. BEIS3 processing

The concepts in BEIS3 are similar to those in BEIS2, except the program Normbeis3 (instead of Rawbio) reads gridded land use data from three files in I/O API input format (BELD3_A, BELD3_B, and BELD3_TOT). Most users rely on the BELD3 database to generate these gridded land use files, but other land use databases may be used, provided the vegetation types and file formats are consistent with the BELD3_A, BELD3_B, and BELD3_TOT files. This database consists of high-resolution (1-km horizontal resolution) land use data for 230 land use types. Normbeis3 creates normalized biogenic emissions for both winter and summer. The Tmpbeis3 program reads the MCIP meteorology data and makes these adjustments; these include the effects of temperature and solar radiation. The winter emission factors are to be used during the "winter" period, which is defined as being after the first date of freezing ground temperature and before the last date of freezing ground temperature. The SMOKE Metscan program can determine this time period and create a gridded file that indicates whether each grid cell is in a winter or summer period for each day of the year. Using this file, which is optional, will cause Tmpbeis3 to read and use both the winter and summer normalized emissions files from Normbeis3. Whether the winter or summer normalized emissions are used for a given grid cell and hour is set by the output from the Metscan program. Users can define the chemical species that are output from Tmpbeis3 using the speciation profile file, GSPRO. In this file, you can set an environment variable (BIOG_SPRO) that indicates which speciation profile code should be used for biogenic emissions. Note that this GSPRO file is different than the one used for BEIS2. More information on Normbeis3 and Tmpbeis3 is provided in Section 6.12, “Normbeis3 and Section 6.17, “Tmpbeis3.